4×4=U? How to choose the right drive system for your next car

December 4, 2015

Car buyers have more choice than ever before. Not just in terms of what your next car looks like – but right down to the fundamentals of how it drives along the road, or in some cases, goes off-road.

To get their vehicles moving and their customers from A to B, car makers have a number of different ways of sending power from the engine to the wheels.

But simply understanding what all the many names, abbreviations and acronyms mean can be a tall order – let alone choosing the best option to suit your needs.

Basically, each system takes a different approach to how the wheels are used to give more grip in slippery conditions, deliver a sporty driving experience, or even improve fuel efficiency. And, whether you want a 7-seater car, a luxury car, or a sport utility vehicle (SUV), making the right choice is important.

Front-wheel drive

Front-wheel drive (FWD), which means power is sent only to the two front wheels, has in recent decades been the most common approach taken by many car makers.

FWD enables the engine, gearbox and mechanicals to be placed at the front of the car, under the bonnet. This can save weight, which improves fuel efficiency, and also frees space in the cabin for the driver, passengers and luggage. This is ideal for smaller cars like the Ford Fiesta.

Placing the weight of the engine over the power wheels also helps to keep the tyres firmly on the road, lessening the likelihood of wheel spin in slippery conditions.

However, because FWD means the front wheels both drive and steer the car, a FWD design copes less well with a powerful engine, and generally is not as good at going around corners as some other designs.

Rear-wheel drive

Rear-wheel drive (RWD) means power is sent only to the rear wheels, enabling the front wheels to concentrate purely on steering. This can result in a more responsive steering feel and sporty driving experience, especially for higher performance models like the Ford Mustang.

Although some sports cars have their engine in the middle or even at the rear, most RWD cars send power from an engine at the front to the rear wheels using a shaft that runs the length of the car. This can improve the weight balance of the car making it better at going around corners, but can increase weight – reducing fuel efficiency. It also can require a hump or transmission tunnel for the shaft, which takes up space along the cabin floor.

With less weight over the power wheels, RWD cars can be trickier to drive in slippery conditions.

Four-wheel drive

Four-wheel drive (4WD) systems send the power to all four wheels. Sometimes called 4×4 or four-by-four, they were the driving force behind military vehicles like the Jeep. The systems usually require drivers to manually shift into 4WD mode, although sometimes they are permanently engaged in 4WD.

A 4WD system is usually found in off-road vehicles designed to tackle very tough terrain like the Ford Ranger, and can lock the front and rear axles together, providing a 50/50 front-to-rear power split.

Some 4WD systems go further, enabling a lower range of gears to be selected for climbing or descending steep slopes, and locking the rear wheels together so that they always rotate at the same speed – an advantage over uneven terrain.

Today, 4WD is available in many SUVs, as well as commercial and utility vehicles.

All-wheel drive

All-wheel drive (AWD) is a technology that can use sophisticated electronics to send power either to the front wheels, or to the rear wheels, or to both at the same time.

AWD continually monitors conditions and only sends power where it is needed; able to adjust how much power is delivered to the wheels from the engine several times a second.

System such as Ford’s Intelligent AWD are popular with drivers of crossover cars and SUVs like the Ford Edge and Kuga, as they can deliver the additional grip of 4WD while using less fuel. Intelligent AWD also can deliver a smoother and quieter driving experience, and is now available on different types of vehicle including the Ford S-MAX and Mondeo.

AWD can help drivers in slippery conditions, when towing a caravan or trailer, and when driving off road, by sensing when a wheel is slipping and sending power to the wheels that have better grip.

AWD also can improve a vehicle’s agility by sending power to the rear when cornering, and in some cases can split the power delivery from side-to-side for a sportier driving experience, as with the Ford Focus RS.

While AWD can vastly increase a vehicle’s off-road capability, it generally does not offer true go-anywhere capability.

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